What is cholesterol?
Cholesterol is any one of a class of certain organic molecules called lipids. It is a sterol (or a modified steroid), a lipid. Cholesterol is biosynthesized by all animal cells and is an important structural component of animal cell membranes. It is a pale yellow crystalline solid when chemically isolated.
Cholesterol is also a precursor for the biosynthesis of steroid hormones, bile acids, and vitamin D. Cholesterol is the main sterol synthesized by all animals. In vertebrates, hepatocytes usually produce the largest amount. It is absent in prokaryotes (bacteria and archaea), with some exceptions, such as mycoplasma, which requires cholesterol to grow.
François Poulletier de la Salle first discovered solid cholesterol in gallstones in 1769. However, it was not until 1815 that the chemist Michel Eugène Chevreul named the compound "cholesterol".
Where does cholesterol come from?
The liver and intestines make about 80% of the cholesterol in the body, as cholesterol is essential to proper bodily function. Only about 20% of the cholesterol in the body comes from the foods that a person eats.
Cholesterol in your body comes from two main sources: your liver and your diet.
Your liver, other organs, and other cells in your body produce about 80 percent of the cholesterol in your blood.
The other 20 percent of cholesterol in your body is affected by the foods you eat. Foods high in trans and saturated fats can contribute to unhealthy cholesterol levels.
As you take in more of these fats, your liver compensates by reducing its own production of cholesterol and removing excess cholesterol. However, not everyone makes and removes cholesterol with the same efficiency.
Some people have genes that tell their liver to make extra cholesterol or to slow their body’s cholesterol removal process. If you’ve inherited these genes, you may have high cholesterol even if you don’t eat foods that are rich in fat or cholesterol.
What happens to cholesterol in the body?
Triglycerides are fat storage molecules that circulate around the body and serve as a source of energy. Both triglycerides and cholesterol are insoluble in water. Therefore, they need protein molecules called lipoproteins to transport them around the body in the blood.
The main types of lipoproteins that the body uses to transport lipids (fats) in the body are:
- Chylomicrons: These large particles transport dietary triglycerides and cholesterol from the intestine to the liver and other body tissues.
- Very low-density lipoproteins (VLDL): The liver produces these particles. Muscle and adipose tissues metabolize VLDL into low-density lipoproteins (LDL).
- LDL: Small dense LDL particles carry most of the cholesterol in the body’s circulation to the tissues. LDL enters the arteries, and free radicals can oxidize it, causing atherosclerosis.
- High-density lipoproteins (HDL): These particles play an important role in transporting cholesterol back to the liver, which helps prevent it from being deposited in arteries. HDL has antioxidant and anti-inflammatory properties, which can inhibit atherosclerosis.
Doctors measure these lipoprotein levels to help them look at a person’s overall risk of heart disease and stroke.
Because having too much LDL in the body can raise the risk of heart disease, people sometimes refer to it as “bad” cholesterol. Conversely, because having high levels of HDL cholesterol is beneficial, some people may call this “good” cholesterol.
How to lower cholesterol ?
If you have high cholesterol, your doctor may recommend lifestyle changes to help lower your cholesterol. For example, they may recommend changes in your diet, exercise habits, or other aspects of your daily life. If you smoke tobacco products, they may recommend that you quit smoking.
Your doctor may also prescribe medications or other treatments to help lower your cholesterol levels. In some cases, they may refer you to a specialist for more care. Find out how long it may take for your cholesterol treatment to work.
To help you achieve and maintain healthy cholesterol levels, your doctor may recommend changes in your diet.
For example, they may recommend that you
- Limit your intake of foods high in cholesterol, saturated fats and trans fats
- Choose lean protein sources, such as chicken, fish and beans
- Eat a variety of high-fiber foods, such as fruits, vegetables and whole grains
- Choose foods that are baked, grilled, steamed, roasted and roasted rather than fried
- Avoid fast food and junk food
Foods that are high in cholesterol, saturated fat or trans fat include:
- Red meat, organ meats, egg yolks and high-fat dairy products
- Processed foods made with cocoa butter, palm oil or coconut oil
- Fried foods, such as potato chips, onion rings and fried chicken
- Certain baked goods, such as some cookies and muffins
Summary
The liver and intestines produce cholesterol to help make cell membranes, hormones, and vitamin D. Cholesterol is a crucial substance for health, but having too much of the wrong type can raise a person’s risk of heart disease.
People do not need to consume cholesterol from foods because the body makes all that it needs. However, consuming cholesterol in eggs is not harmful as part of a healthy diet.
To keep the risk of heart disease low, people should try to limit their intake of saturated fat, trans fat, and sugar in foods and beverages. They should also aim to maintain a healthy lifestyle that includes activity and limits alcohol intake.
People can ask a doctor for a cholesterol test, and they should do this on a regular basis, as high cholesterol rarely causes any symptoms.
References：
1. High cholesterol - Symptoms and causes - Mayo Clinic
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